In the past, there have been various remote device monitoring systems (home appliance monitoring systems) (cf. JP 2004-320260 A).
Particularly, in the home appliance monitoring system used for remote monitoring, each central managing device collects monitoring information (detection result) from home appliances such as a thermo-hygrometer, a wattmeter, a sensor measuring lighting period of a lighting fixture, and a human sensor. In addition, a center server obtains the monitoring information of the home appliance under each central managing device, and stores the obtained information.
With respect to the aforementioned home appliance monitoring system where the center server obtains the monitoring information from each central managing device, loads on the center server will increase as a system size is increased with an increase of the number of the central managing devices. To reduce the loads on the center server requires an increase of the number of the center servers and improvement of the performance of the center server, for example. However, there is a problem that such a method against the expansion of the system scale needs high cost.